Transfer pumps

ABSTRACT

In order to enable a fuel transfer pump constructed as an axialflow impeller pump to remain effective to a very low fuel level in a tank, the axis of the pump is arranged at an angle to the vertical so that the impeller inlet face forms an angle with the tank bottom. Preferably the impeller projects below the lower end of a shroud housing, the edge of the projecting impeller portion and the end surface of the shroud is tapered to have a tangential plane parallel to the tank bottom.

United States Patent 1 Colliver et al.

[ July 3,1973

[ TRANSFER PUMPS [75] inventors: Harold Edward Sydney Colliver;

Gerald Eric Boby; Dennis Dewhurst Farmer, all of llford, England [73]Assignee: The Plessey Company Limited,

Ilford, England 22 Filed: Feb. 17,1972

21 Appl. No.: 227,567

Related US. Application Data [63] Continuation of Ser. No. 30,698, April22, 1970,

abandoned.

[52] US. Cl 415/204, 415/219 R, 222/385, 417/424 [51] Int. Cl F04d29/40, B67d 5/48 [58] Field of Search 415/213, 215; 2/204, 2/206;417/231, 424; 222/385; 250/7, 42, 97

[56] References Cited UNITED STATES PATENTS 536,998 4/1895 Bennett416/189 2,214,677 9/1940 North 417/231 2,698,583 1/1955 House et al..417/231 2,860,835 11/1958 Schade 417/424 3,148,464 9/1964 Jones 37/67Primary Examiner-Henry F. Raduazo Attorney-Harold 1. Kaplan [5 7ABSTRACT ln order to enable a fuel transfer pump constructed as anaxial-flow impeller pump to remain effective to a very low fuel level ina tank, the axis of the pump is arranged at an angle to the vertical sothat the impeller inlet face forms an angle with the tank bottom.Preferably the impeller projects below the lower end of a shroudhousing, the edge of the projecting impeller portion and the end surfaceof the shroud is tapered to have a tangential plane parallel to the tankbottom.

12 Claims, 1 Drawing Figure PAIENIEDJUL 3 I973 3. 743,438

TRANSFER PUMPS This a continuation of application Ser. No. 30,698, filedApr. 22, 1970.

DISCLOSURE This invention relates to fuel-transfer pumps. A fueltransferpump serves to withdraw fuel from a fuel tank and deliver it to a placeof consumption, for example to the fule pump of a combustion engine,generally with the interposition of a further so-called backing pumpwhich serves to raise the pressure level of the fuel entering the fuelpump proper. It is an object of the present invention to provide animproved transfer pump which can effectively deal with the transfer ofliquid from a tank even when the liquid level in the tank is very low. Aknown kind of transfer pump is of the axialflow impeller type and isarranged in a fuel tank with its axis vertical, the impeller beingaccommodated in a shroud, and while this kind of pump workssatisfactorily so long as the fuel level is reliably above the lower endof the shroud in which the impeller is accommodated, its effectivenessceases when the fuel level falls below the fuel-entrance end of theshroud, Since the entrance end of the shroud must be spaced from thebottom of the tank sufficiently not to obstract the access of liquid tothe impeller inlet, a certain amount of fuel, determined by the level ofthe entrance end of the shroud, cannot be withdrawn from the tank by theknown pumps.

The present invention has for a more specific object to make it possibleto withdraw liquid from the tank down to an appreciably lower level.According to the invention the transfer pumpo is an axial-impeller pumpin which the entrance-end face of the shroud is inclined at an angle tothe bottom of the tank, with a complementary inclination of the axis ofthe impeller, thus ensuring that, even if the impeller end faceapproaces the tank bottom very closely at one side, the access of liquidto the entrance of the impeller and shroud is relatively free since, dueto the inclination of the entrance face, the mean amount of spacingbetween the impeller end face and the tank bottom is relatively largewith the spacing increasing from a point of closest approach to thediameterically opposite point.

In order to permit pumping to be effected up to the lowest possiblelimit, the impeller is preferably arranged to project beyond theentrance end of the shroud, and this projecting end portion of theimpeller is preferably tapered so that its outer surface defines a conesurface having a tangential plane parallel to the tank bottom at a closedistance from the latter. The entrance-end face of the shroud wall ispreferably likewise tapered to form a continuation of this cone surface.

The accompanying part of a fuel tank in section and a transfer pumpconstructed and arranged in accordance with one embodiment of theinvention.

Referring now to the drawing, the pump is mounted in a fuel tank 1,whose bottom is shown in vertical section. A pump housing 2, forming animpeller shroud in which an impeller 3 is rotatable abouta longitudinalaxis 4, is supported on the tank bottom by a column 5 in such a mannerthat the inlet or entrance face 6 of the impeller and of the shroud isinclined at an angle a to the tank bottom, the same angle a beingenclosed between the impeller axis 4 and the normal direction of drawingis an elevation showing gravity. in the illustrated embodiment the pumphousing 2 is further provided with a lateral outlet stud 7 for theliquid delivered, and at its end remote from the inlet end 66 thehousing contains an electric motor schematically indicated at 8, theelectric supply wires to which may pass through the colum 5. As can bevseen in the drawing, the lower end of the impeller 3 projects beyond thelower end face of the shroud portion of the housing 2 and is tapered toprovide a cone portion 9 with a cone angle of 2 (1r a) so that it has atangential surface parallel to the bottom of the tank 1, thus com biningmaximum freedom of liquid access of liquid from the tank to the impellerinlet with a close approach of the impeller to the tank bottom over arelatively large area. The inclination of the end surface 6 relative tothe tank bottom also offers the advantage that any air or vapour whichis liable to enter the pump with the fuel as the fuel level goes down,will be automatically returned to the tank at the side of the inlet face6 remote from the point of its closest approach to the tank bottom. Theinlet end face 10 of the impeller shroud is arranged to form acontinuation of the surface of cone portion 9 of the impeller 3.

It will be evident to those skilled in the art that various details ofthe embodiment described may be moditied without departing from thescope of the invention. Thus the outlet of the liquid delivered by thepump could be arranged axially, or a radial impeller portion might bearranged at the outlet end of the axial impeller, thus facilitating,generally with the assistance of a volute outlet, the supply of liquidat a higher outlet pressure.

What we claim is:

l. A liquid axial flow fuel transfer pump for installation in a fueltank having a flat bottom wall portion, said pump comprising a. atubular casing having a longitudinal axis and an inlet face normal tosaid longitudinal axis and an annular wall adjacent said inlet divergingfrom said axis;

b. an axial flow impeller mounted for axial rotation in said tubularcasing and along said longitudinal axis, said axial flow impeller havingan upstream end portion which extends at least substantially to saidinlet face and which is such that, during use of said fuel supply unit,the fuel engages said upstream end of said impeller and is forced intosaid tubular casing through said inlet face; and

. supporting means for rigidly attaching said tubular casing at an acuteangle to said bottom wall portion with said inlet face making an acuteangle with a plane of said bottom wall portion and said annular wall isin close proximity to said bottom wall portion.

2. A transfer pump as'cla'imed in claim 1 in which said upstream end ofsaid axial flow impeller projects upstream beyond said inlet face.

3. A liquid axial flow fuel transfer pump for installation in a fueltank having a flat bottom wall portion, said pump comprising a tubularcasing element, said casing element having a first inlet end portionconstituted by an outward diverging frustro-conical surface and saidcasing terminating in a downstream substantially cylindrical portion, anaxial flow impeller in said tubular casing element and mounted on theaxis of said cylindrical portion, said axial flow impeller having anupstream end portion conforming to the shape of the outwardly divergingfrustro-conical surface of said inlet end portion and projectingupstream out of said inlet whereby the pump liquid engages said upstreamend of said impeller and is forced into the frustro-conical divergingend portion of said casing element, and a supporting means for rigidlyattaching said tubular casing element at an acute angle to said flatbottom wall portion, whereby said projecting upstream end portion ofsaid impeller and diverging end of said casing element lie in closeproximity to and parallel to said flat bottom wall portion.

4. A transfer pump as claimed in claim 3 in which said outward divergingfrustro-conical surface is followed by a downstream converging conicalsurface.

5. A fuel supply unit which comprises, in combination:

A. a fuel tank having a substantially flat bottom wall portion;

B. a liquid axial-flow fuel-transfer pump comprising 1. a tubular casinghaving a longitudinal axis and an inlet face normal to said longitudinalaxis and an adjacent surface to said inlet diverging from said axis;

2. an axialflow impeller mounted for axial rotation in said tubularcasing and along said longitudinal axis, said axial flow impeller havingan upstream end portion which extends at least substantially to saidinlet face and which is such that, during use of said fuel supply unit,the fuel engages said upstream end of said impeller and is forced intosaid tubular casing through said inlet face; and

C. supporting means for rigidly attaching said tubular casing at anacute angle to said bottom wall portion with said inlet face making anacute angle with said bottom wall portion and said adjacent surface in aplane in close proximity to said bottom wall portion.

6. A fuel supply unit as claimed in claim 5 in which said upstream endof said axial flow impeller projects upstream beyond said inlet face.

7. A fuel supply unit as claimed in claim 5 in which said longitudinalaxis of said tubular casing forms an angle of approximately 60 with saidbottom wall portion.

8. A fuel supply unit which comprises, in combination: a fuel tankhaving a substantially flat bottom wall portion, and a liquid axial flowfuel transfer pump for installation in a fuel tank having a flat bottomwall portion, said pump comprising a tubular casing element, said casingelement having a first inlet end portion constituted by an outwarddiverging frustro-conical surface and said casing terminating in adownstream substantially cylindrical portion, an axial flow impeller insaid tubular casing element and mounted on the axis of said cylindricalportion, said axial flow impeller having an upstream end portionconforming to the shape of the outwardly diverging frustro-conicalsurface of said inlet end portion and projecting upstream out of saidinlet whereby the pump liquid engages said upstream end of said impellerand is forced into the frustro-conical diverging end portion of saidcasing element, and a supporting means for rigidly attaching saidtubular casing element at an acute angle to said flat bottom wallportion, whereby said projecting upstream end portion of said impellerand diverging end of said casing element lie in close proximity to andparallel to said flat bottom wall portion.

9. A liquid axial flow fuel transfer pump for installation in a fueltank having a flat bottom wall portion, said pump comprising a. atubular casing having a longitudinal axis and an inlet face normal tosaid longitudinal axis, said tubular casing being constituted by adiverging frustro-conical portion followed by a downstream convergingfrustro-conical portion, and terminating in a downstream substantiallycylindrical portion; b. an axial flow impeller mounted for axialrotation in said tubular casing and along saidlongitudinal' axis, saidaxial flow impeller having an upstream end portion which extends atleast substantially to said inlet face and which is such that, duringuse'of said fuel supply unit, the fuel engages said-upstream end of saidimpeller and is forced into said tubular casing through said inlet face;and

c. supporting means for rigidly attaching said tubular casing at anacute angle to said bottom wall portion with said inlet face having thediverging frustoconical wall portion making an acute angle with a planein close proximity to said bottom wall portion.

10. A transfer pump as claimed in claim 9 in which said up-stream end ofsaid axial flow impeller conforms to the shape of said divergingfrustro-conical portion and projects upstream beyond said inlet face.

11. A fuel supply unit which comprises, in combination:

A. a fuel tank having a substantially flat bottom wall portion; 1

B. a liquid axial-flow fuel-transfer pump comprising 1. a tubular casinghaving a longitudinal axis and an inlet face normal to said longitudinalaxis, said tubular casing being constituted by a divergingfrustro-conical portion followed by a downstream convergingfrustro-conical portion, and terminating in a downstream substantiallycylindrical portion.

2. an axial flow impeller mounted for axial rotation in said tubularcasing and along said longitudinal axis, said axial flow impeller havingan upstream end portion which extends at least substantially to saidinlet face and which is such that, during use of said fuel supply unit,the fuel engages said upstream end of said impeller and is forced intosaid tubular casing through said inlet face; and

C. supporting means for rigidly attaching said tubular casing at anacute angle to said bottom wall portion with said inlet face having thediverging frustoconical portion making an acute angle with a plane inclose proximity to and parallel to said bottom wall portion.

12. A fuel supply unit as claimed in claim 1 l in which said upstreamend of said axial flow impeller conforms to the shape of said divergingfrustro-conical portion and projects upstream beyond said inlet face.

l i i I!

1. A liquid axial flow fuel transfer pump for installation in a fueltank having a flat bottom wall portion, said pump comprising a. atubular casing having a longitudinal axis and an inlet face normal tosaid longitudinal axis and an annular wall adjacent said inlet divergingfrom said axis; b. an axial flow impeller mounted for axial rotation insaid tubular casing and along said longitudinal axis, said axial flowimpeller having an upstream end portion which extends at leastsubstantially to said inlet face and which is such that, during use ofsaid fuel supply unit, the fuel engages said upstream end of saidimpeller and is forced into said tubular casing through said inlet face;and c. supporting means for rigidly attaching said tubular casing at anacute angle to said bottom wall portion with said inlet face making anacute angle with a plane of said bottom wall portion and said annularwall is in close proximity to said bottom wall portion.
 2. A transferpump as claimed in claim 1 in which said upstream end of said axial flowimpeller projects upstream beyond said inlet face.
 2. an axial flowimpeller mounted for axial rotation in said tubular casing and alongsaid longitudinal axis, said axial flow impeller having an upstream endportion which extends at least substantially to said inlet face andwhich is such that, during use of said fuel supply unit, the fuelengages said upstream end of said impeller and is forced into saidtubular casing through said inlet face; and C. supporting means forrigidly attaching said tubular casing at an acute angle to said bottomwall portion with said inlet face making an acute angle with said bottomwall portion and said adjacent surface in a plane in close proximity tosaid bottom wall portion.
 2. an axial flow impeller mounted for axialrotation in said tubular casing and along said longitudinal axis, saidaxial flow impeller having an upstream end portion which extends atleast substantially to said inlet face and which is such that, duringuse of said fuel supply unit, the fuel engages said upstream end of saidimpeller and is forced into said tubular casing through said inlet face;and C. supporting means for rigidly attaching said tubular casing at anacute angle to said bottom wall portion with said inlet face having thediverging frusto-conical portion making an acute angle with a plane inclose proximity to and parallel to said bottom wall portion.
 3. A liquidaxial flow fuel transfer pump for installation in a fuel tank having aflat bottom wall portion, said pump comprising a tubular casing element,said casing element having a first inlet end portion constituted by anoutward diverging frustro-conical surface and said casing terminating ina downstream substantially cylindrical portion, an axial flow impellerin said tubular casing element and mounted on the axis of saidcylindrical portion, said axial flow impeller having an upstream endportion conforming to the shape of the outwardly divergingfrustro-conical surface of said inlet end portion and projectingupstream out of said inlet whereby the pump liquid engages said upstreamend of said impeller and is forced into the frustro-conical divergingend portion of said casing element, and a supporting means for rigidlyattaching said tubular casing element at an acute angle to said flatbottom wall portion, whereby said projecting upstream end portion ofsaid impeller and diverging end of said casing element lie in closeproximity to and parallel to said flat bottom wall portion.
 4. Atransfer pump as claimed in claim 3 in which said outward divergingfrustro-conical surface is followed by a downstream converging conicalsurface.
 5. A fuel supply unit which comprises, in combination: A. afuel tank having a substantially flat bottom wall portion; B. a liquidaxial-flow fuel-transfer pump comprising
 6. A fuel supply unit asclaimed in claim 5 in which said upstream end of said axial flowimpeller projects upstream beyond said inlet face.
 7. A fuel supply unitas claimed in claim 5 in which said longitudinal axis of said tubularcasing forms an angle of approximately 60* with said bottom wallportion.
 8. A fuel supply unit which comprises, in combination: a fueltank having a substantially flat bottom wall portion, and a liquid axialflow fuel transfer pump for installation in a fuel tank having a flatbottom wall portion, said pump comprising a tubular casing element, saidcasing element having a first inlet end portion constituted by anoutward diverging frustro-conical surface and said casing terminating ina downstream substantially cylindrical portion, an axial flow impellerin said tubular casing element and mounted on the axis of saidcylindrical portion, said axial flow impeller having an upstream endportion conforming to the shape of the outwardly divergingfrustro-conical surface of said inlet end portion and projectingupstream out of said inlet whereby the pump liquid engages said upstreamend of said impeller and is forced into the frustro-conical divergingend portion of said casing element, and a supporting means for rigidlyattaching said tubular casing element at an acute angle to said flatbottom wall portion, whereby said projecting upstream end portion ofsaid impeller and diverging end of said casing element lie in closeproximity to and parallel to said flat bottom wall portion.
 9. A liquidaxial flow fuel transfer pump for installation in a fuel tank having aflat bottom wall portion, said pump comprising a. a tubular casinghaving a longitudinal axis and an inlet face normal to said longitudinalaxis, said tubular casing being constituted by a divergingfrustro-conical portion followed by a downstream convergingfrustro-conical portion, and terminating in a downstream substantiallycylindrical portion; b. an axial flow impeller mounted for axialrotation in said tubular casing and along said longitudinal axis, saidaxial flow impeller having an upstream end portion which extends atleast substantially to said inlet face and which is such that, duringuse of said fuel supply unit, the fuel engages said upstream end of saidimpeller and is forced into said tubular casing through said iNlet face;and c. supporting means for rigidly attaching said tubular casing at anacute angle to said bottom wall portion with said inlet face having thediverging frusto-conical wall portion making an acute angle with a planein close proximity to said bottom wall portion.
 10. A transfer pump asclaimed in claim 9 in which said up-stream end of said axial flowimpeller conforms to the shape of said diverging frustro-conical portionand projects upstream beyond said inlet face.
 11. A fuel supply unitwhich comprises, in combination: A. a fuel tank having a substantiallyflat bottom wall portion; B. a liquid axial-flow fuel-transfer pumpcomprising
 12. A fuel supply unit as claimed in claim 11 in which saidupstream end of said axial flow impeller conforms to the shape of saiddiverging frustro-conical portion and projects upstream beyond saidinlet face.